This invention relates to ventilation units; for example in heating systems and air conditioning systems.
FIG. 1 shows a typical prior art air conditioning system for a vehicle. Air is drawn inwards through inlet 1 by a radial blower 2 running in a scroll 3. This forces air through evaporator 4. From the evaporator the air meets a blend door 5 which can pivot about a hinge 6. The blend door divides the airflow from the evaporator into a first (cold) stream which passes directly to a mixing chamber 7 and a second (hot) stream which passes through a heater core 8 on its way to the mixing chamber. The hot and cold air streams recombine and mix together in the mixing chamber. At the outlet of the mixing chamber is a movable panel door 9 which divides the air from the mixing chamber into a stream directed through outlet 10 towards the vehicle's panel and a remaining stream directed through passage 11 to a movable floor/defrost door 12. The floor/defrost door divides that remaining stream between the vehicle's floor and defrost outlets. The blend door 5 can be moved to control the temperature of the outgoing air by setting the amount of air in the hot and cold streams. The doors 9 and 12 are movable by a user to set the desired flow pattern in the vehicle.
For proper operation of the system the hot and cold air streams must be properly mixed by the time they reach the panel door. To achieve this the mixing chamber must be of a sufficient length. This occupies considerable space.
One aim of this invention is to reduce the space occupied by the system. Another aim is to allow a user to have the air flows to the panel vents and to the other outlets at different temperatures.